I'm not sure why but Drupal doesn't provide for a horizontal user login with the register or forgot password links. How do I do this?
There are many many ways to do this, there is even a screencast and a module to do this. I would personally do this from the theme layer using css, or if I was using Fusion as a base theme, I would do this from the block configuration (thanks Skinr!)
I'm adding some links that will help you out.